Free Access

Fig. 2


Sound speed (red) and density (blue) in the upper layers of the Sun as functions of height measured from the photosphere. Below 500 km (vertical dashed line), the sound speed and density are from model S (Christensen-Dalsgaard et al. 1996). Above 500 km, the model Atmo (solid lines) consists of an extension where density decays exponentially (H = 105 km) and sound speed is constant (c = 6855 m/s). The dashed lines show the VAL-C atmospheric model up to a height of 2500 km (Vernazza et al. 1981), which will be used in Sect. 6.

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.